Pharmaceutical tablets coated with wax-free ammonia solubilized water soluble shellac



United States Patent 3,390,049 PHARMACEUTICAL TABLETS COATED WITHWAX-FREE AMMONIA SOLUBILIZED WATER SOLUBLE SHELLAC Alvin B. Rcdnicit,Cherry Hill, N.J., and Michael.

Secora, Phiiadelphia, Pa., assignors to Smith Kline & FrenchLaboratories, Philadelphia, Pin, a corporation of Pennsylvania NoDrawing. Filed Dec. 23, 1964, Ser. No. 420,771 3 Claims. (Cl. 167-82)ABSTRACT OF THE DIStlLOSURE Thin film coated pharmaceutical forms whichemploy a water soluble shellac as the coating material. Wax-free shellacis rendered water soluble by dissolving it in ammonia and Waterresulting in a water permeable coating.

This invention relates to a novel film coating composition for solidpharmaceutical forms such as compressed tablets, pills, pellets and thelike, a pharmaceutical form substantially covered with said coating anda rapid and inexpensive process for coating said forms.

More specifically this invention relates to coated pharmaceutical formshaving a novel film coating which has as a main ingredient Water solubleshellac.

Shellac is Well known as a coating material in the art. However,whenever shellac is employed as a coating agent for a pharmaceuticalform the prior art reveals that the coated product is either enteric orsustained release in nature. In other words when a tablet is coated withshellac the prior art teaches that the tablet will possess a delayedrelease of medicament.

Further, shellac has been utilized to cover tablets that have beenpreviously sugar coated in order to facilitate printing or to provide awaterproof or moisture barrier for a tablet core prior to sugar coating.In each instance sugar coating of the tablet is an additional step.

The process of sugar coating tablets embraces the following timeconsuming coating steps:

(a) waterproofing and sealing,

(b) subcoating,

(c) rounding or smoothing coats, (d) coloring and finishing coats and(e) polishing.

This amounts to approximately 80 total coats and takes days to complete.This total time is required not only because of the number of coatsnecessary but also because of the drying cycle needed before applyingthe next coat.

Disadvantages associated with the build up of sugar coating layers areobvious. For example, sugar coating cannot be used for coating scored orgrooved tablets and tablets with engraved monograms because the totalnumber of coats required obliterates the groove and monogram. Further,due to the multiple coatings the finished tablet is approximately 50%greater in volume or usually double the weight of the uncoated tablet. Astill further drawback is that the tablet must be compressed relativelyhard in order to withstand the vigorous rolling and tumbling in thecoating pan. This hard compression often results in a delay indisintegration time.

When the novel coating composition is applied to pharmaceutical formsaccording to the process of this invention it is possible to obtain afast drying, thin, transparent film coat. Sugar coating with all of itsbuild up steps is completely eliminated. The time required to coat thetablets is reduced from days to minutes because of the relatively fewcoats that are necessary. Therefore, in

3.3%,049 Patented June 25, 1968 accordance with this invention it is nowpossible to coat tablets rapidly and inexpensively. The thin,transparent film allows for the monogramming and. scoring of thecompressed tablet. Furthermore, the constituents of the film are allmaterials readily used for human consumption.

More important the tremendous reduction of the number of coats alsoresults in the production of a much smaller finished tablet. Thisfeature allows for a more pharmaceutically elegant tablet which is mucheasier for the patient to swallow.

It has been unexpectedly discovered that when shellac is rendered watersoluble as described hereinafter a superior thin film coating fortablets results. Such water soluble shellac no longer delays the releaseof the tablet but contrary to the prior art teachings results in animmediate release of the tablet. Still further, contrary to prior artteachings the shellac as treated according to the process of thisinvention no longer acts as a Waterproof or moisture barrier but as athin water permeable tablet coating.

The coating composition of this invention is comprised of wax freeshellac which is rendered Water soluble by dissolving the shellac inwater and ammonia until a solution results. Other ingredients such asplasticizing agents, opaquing agents and coloring materials may be addedto the coating solution to enhance the properties of the coating.

Preferably the shellac will be present in an amount of from about 0.1%to about 5% by weight of the total coating composition advantageouslyfrom about 1% to about 3% by weight of the total coating composition.The ratio of water and ammonia to the wax free shellac would be evidentto one skilled in the art, using just enough necessary to dissolve theshellac. Preferably twice as much water and 28% ammonia solution(U.S.P.) used in a ratio of from about 10:1 to about 30:1 is used todissolve the shellac. If desired an or anic solvent may be added to theabove shellac concentrate to hasten the evaporation of the coating.

When plasticizers are advantageously employed in the coating compositionthey will be present in an amount of from about 0.5% to about 15% byweight of the total coating composition preferably from about 1% toabout 10% by Weight of the total coating composition. Among theplasticizing agents which may be employed are any of those well known tothe art, such as for example, solid polyethylene glycol,polyvinylpyrrolidone, dibutyl phthalate, dimethyl phthalate, diisobutyiadipate, castor oil, mineral oil, propylene glycol, stearyl alcohol,cetyl alcohol and the glyceridcs of higher fatty acids.

Most advantageously solid polyethylene glycol and polyvinylpyrrolidoneare used either alone or preferably a mixture of both as plasticizers incarrying out the method of this invention. When this novel combinationof water soluble shellac, solid polyethylene glycol andpolyvinylpyrrolidone is employed it imparts improved iiowability andresults in a coating composition which is more flexible and smoother.Further, the added ingredient, solid polyethylene glycol also acts as ananti-tacking agent and prevents the sticking of the tablets to oneanother as they are rotated in the coating pan. Finally, the use of asolid polyethylene glycol, such as for example, polyethylene glycol6000, adds gloss to the tablet coat and eliminates the necessity of afinal separate polish coating.

The polyethylene glycols used in the coating composition of thisinvention are solid, waxy materials having a molecular weight as high as20,000. Preferably the polyethylene glycols employed will have amolecular weight of from about 1,000 to about 10,000. These solid poly-9 ethylene glycols are well known in the art and sold under thetradename of Carbowax.

When coloring materials are desired, any of the nontoxic pigments, lakesand dyes which have been certified for use in the food, drug andcosmetic industries may be used. The nontoxic coloring agent, whenemployed will be present in an amount to provide the desired color andshade preferably from about 0.05% to about 1% by weight of the totalcoating composition. Exemplary of the preferred dyes and lakes are thosecoal tar colors listed under their Food and Drug Administrationdesignations such as, for example FD & C blue No. 6, D 8; C blue No. 9,D & C green No. 6, D 8: C violet No. 2, D 8: C red No. 17, D & C orangeNo. 5, D 81 C yellow No. 7, D & C green No. 1, PD & C yellow No. 6 lake,FD & C blue No. 2 lake, FD & C red No. 2 lake, FD & C violet No. 1 lakeand FD & C green No. 3 lake.

Advantageously the compositions of this invention may also contain asubstantially water insoluble, colorless, nontoxic opaque material suchas calcium carbonate, barium sulfate or preferably titanium dioxide. Thenontoxic opaque constituent when employed will amount to from about0.25% to about by weight of the coloring composition.

The novel coating composition is prepared by first forming the shellacconcentrate by dissolving the wax free shellac and when employed, theplasticizer in Water and strong ammonia solution. The shellacconcentrate is then diluted with organic solvents, such as for example,alcohol and chloroform containing either the dye, pigment or lake. Thecoating composition is now ready for use and it may be poured or sprayedon the solid pharmaceutical forms.

The method of coating the solid pharmaceutical forms such as compressedtablets, pills, pellets, troches and the like in accordance with thisinvention comprises placing said solid forms, as for example tabletscontaining a medicament and filler, in a coating pan. The tablets arethoroughly and evenly wetted with the coating solution. The tablets aredried while rotating in the coating pan. Advantageously air is passedover the tablets during the drying process. Further coats are applied byrepeating the above procedure. Normally 10 to coats are sufficient, morecan be applied if desired. The coated tablets can be polished or not asdesired.

The solid pharmaceutical forms which are also an important aspect ofthis invention are solid pharmaceutical forms such as tablets, pills,pellets, troches and the like substantially completely coated with afilm forming polymer containing water soluble shellac as defined above.These forms are comprised of a core containing the medicament normallywith a filler surrounded by said film forming polymer. The thickness ofsaid coatings advantageously is in the range of from about 0.0001 toabout 0.002" preferably from about 0.0005" to about .001". Generally itis satisfactory for the coating to be from about 0.3% to about 3% of thetotal weight of the tablet, preferably from about 0.5% to about 2% andas indicated above it substantially completely covers the core form.

Tablets coated using this procedure and coating composition yield asmooth glossy coat. The total thickness of the combined coats is suchthat the detail of the surface of the core is retained, for instancemonograms or scores.

The following examples are not limiting and are used to specificallyillustrate the coating composition and will make obvious to one skilledin the art the full practice of the method of this invention.

Example 1.Shellac concentrate-Solution A Ingredients: Percent w./v. Waxfree shellac 15.34

Polyvinylpyrrolidone 15.34 Carbowax 6000 14.32 Strong ammonia solution28% (U.S.P.) 1.53

Water, q.s., 100.00 ml.

4- The shellac, polyvinylpyrrolidone and Carbowax are dissolved in thestrong ammonia solution and water with the aid of heat to form a shellacconcentrate.

Solution B Ingredients: Amount Shellac concentrate ml 300 Isopropylalcohol ml 4500 Chloroform ml 600 Titanium dioxide gms 180 ED & C yellowNo. 5 lake gms 18 The shellac concentrate, isopropyl alcohol andchloroform are mixed and the titanium dioxide and FD & C yellow No. 5lake are suspended in the mixture with continued agitation to form thecoating composition. Tablet cores of inch diameter containingtrifiuoperazine and filler are placed in a rotating 12 inch coating panand are thoroughly and evenly wetted by spraying on the above coatingcomposition. The tablets are dried while being rotated and passing airover them. This procedure is followed until approximately 15 coats havebeen applied leaving a hard thin film coat on the tablets.

Example 2.Shellac concentrate--Solution A Ingredients: Percent w./v. Waxfree shellac 20.4 Strong ammonia solution 28% (U.S.P.) 2.04 Distilledwater, q.s., 100.00 ml.

The shellac is dissolved in the strong ammonia solution and the waterwith stirring and the application of heat, approximately heated to C.

Solution B Ingredients: Amount, ml. Shellac concentrate Isopropylalcohol 4500 Chloroform 600 The shellac concentrate, isopropyl alcoholand chloroform are thoroughly mixed to form the coating composition.

Tablet cores containing dextroamphetamine and filler are placed in arotating 12 inch coating pan and are thoroughly and evenly wetted byspraying on the above coating composition. The tablets are dried Whilebeing rotated and passing air .over them. This procedure is followeduntil approximately 15 coats have been applied leaving a hard thin filmcoat on the tablets.

Example 3.Shellac concentrateSolution A Ingredients: Percent w./v. Waxfree shellac 16.0

Carboxaw 6000 15.0 Strong ammonia solution 28% (U.S.P.) 1.6

Water, q.s., 100.0 ml.

The shellac and Carboxaw are dissolved in the strong ammonia solutionand water with the aid of heat to form a shellac concentrate.

Solution B Ingredients: Amount Shellac concentrate ml 200 Isopropylalcohol ml 4500 Chloroform ml 600 FD & C Yellow No. 5 gms 1.8

The shellac concentrate, chloroform and alcohol which has the FD & CYellow No. 5 added are thoroughly mixed to form the coating composition.

Tablet cores containing chlorpromazine hydrochloride and filler areplaced in a rotating 12 inch coating pan and are thoroughly and evenlywetted by spraying on the above coating composition. The tablets aredried while being rotated and passing air over them. This procedure isfollowed until approximately 15 coats have been applied leaving a hardthin film coat on the tablets.

What is claimed is:

1. A film-coated pharmaceutical form comprising a solidmedicament-containing core, that has not been previously coated having acoating that provides neither a water-proof or moisture barrier nor isenteric or sustained release in nature comprising from about 10 to about20 coats of Wax-free ammonia solubilizecl water soluble shellac, saidcoating being from 0.0005 inch to about 0.0-01 inch thick and being fromabout 0.3% to about 3.0% of the total weight of the tablet.

2. A film-coated pharmaceutical form comprising a solidmedicament-containing core that has not been previously coated having acoating that provides neither a Waterproof or moisture barrier nor isenteric or sustained release in nature comprising from about 10 to about20 coats of Wax-free ammonia solubilized Water soluble shellac and aplasticizer selected from the group consisting of polyvinylpyrrolidoneor solid polyethylene glycol said coating being from 0.0005 inch toabout 0.001 inch thick and being from about 0.3% to about 3.0% of thetotal weight of the tablet.

3. A film-coated pharmaceutical form comprising a solidmedicament-containing core that has not been previously coated having acoating that provides neither a water-proof or moisture barrier nor isenteric or substained release in nature comprising from about 10 toabout 20 coats of wax-free ammonia solubilized Water soluble shellac andsolid polyethylene glycol said coating being from about 0.3% to about3.0% of the total weight of the tablet.

References Cited UNITED STATES PATENTS 2,865,810 12/1958 Sanders 167-822,954,322 9/1960 Heilig et 'al 167-82 3,097,144 7/1963 Banker 167-823,149,039 9/1964 Jetfries 167-82 3,149,041 9/1964 Ietlfries 167-823,173,839 3/1965 Nicholson 167-82 3,256,153 6/1966 Heimlich 167-823,297,535 1/1967 Butler et a1. 167-82 2,450,959 10/1948 Heinecke 106-302,678,278 5/1954 Schmitzler 106-30 2,982,234 5/1961 Ackley et a1. 107-542,245,100 6/1941 Bernstein 134-36 LEWIS GOTTS, Primary Examiner.

S. K. ROSE, Assistant Examiner.

